You call the phone, you bring Xiaomi to your ear, and the screen suddenly goes out. The sound remains, but you can't control the conversation: neither complete the call, nor turn on speakerphone. The problem is familiar to many owners of the brand's smartphones, and it is found on both the budget Redmi and flagship Xiaomi 13/14. What is the reason for this behavior and how to get the phone back to normal work?
80 percent of the time, the proximity sensor, the little sensor next to the front camera that detects when you're holding your phone to your ear, but sometimes the root of the problem goes deeper, from firmware failures to physical damage, and in this article, we'll look at all the possible causes, diagnose the malfunction, and give you step-by-step repair instructions, from simple adjustments to parts replacement.
Important: if the screen not only dims, but also completely turns off (the phone turns off) when you call, this may indicate a critical malfunction of the battery or motherboard - in this case, it is better to immediately contact the service center.
1. How the proximity sensor works and why it doesn't work correctly
The proximity sensor is an infrared sensor that measures the distance from the screen to your ear. When you hold the phone to your head, the sensor sends a signal to the system, and the screen goes out to:
- 🔋 Save battery power (screen backlight is one of the main energy consumers).
- 👂 Prevent accidental tapping of the cheek or ear (e.g., turning off a call or dialing a number).
- 📞 Improve communication quality (some models reduce transmission power when the phone is close to the head).
Normally, the screen should turn on as soon as you take the phone away from your ear, and if that doesn't happen, the problem may be:
- 🧹 Sensor contamination (dust, greasy traces, protective film).
- 🔧 Incorrect calibration (settings are lost after updating or resetting).
- 💥 Physical failure (crack in glass, plume damage).
- 🤖 Firmware failure (bug in MIUI or custom firmware).
On most Xiaomi models, the proximity sensor is located to the right of the front camera (see diagram below). To check its performance, you just need to run a sensor test – more about this in the next section.
2.Diagnostics: How to check the proximity sensor on Xiaomi
Before you carry your phone for repair, do a simple diagnostic, which will take no more than 5 minutes and will help determine whether the sensor is to blame or the problem is to blame for another.
Method 1: Testing sensors through an engineering menu
Any Xiaomi smartphone has a hidden engineering menu where you can check the operation of the sensors.
- Open the Phone app.
- Enter the code ##6484## (or #4636## on some models).
- Select the Hardware Testing option → Sensor Test.
- Find the Proximity Sensor string.
- Close the sensor with your hand – the value should change from 5 (far) to 0 (close).
If the values don't change or the sensor is showing 0 constantly, the sensor is faulty. If the values jump randomly (e.g., 5 → 0 → 3 → 1), the sensor is contaminated or poorly calibrated.
Method 2: Verification through third-party applications
If the engineering menu is not available, install one of these apps from Google Play:
- CPU-Z (Sensors section).
- Phone Doctor Plus (Proximity Sensor)
- Sensor Test (from Smart Tools)
🔍 Important! Take off the protective film or the case before the test, and they can block the sensor signal.
Clean the sensor area with alcohol|Take off the film/case|Reboot the phone|Update MIUI last-minute-->
3. Programmatic reasons: MIUI failures and settings
If the sensor is working, but the screen is still dim, the problem may be in the system settings or the firmware bug. Let's take a look at the most common cases.
Reason 1: Calibration of the sensor is lost
After updating MIUI or resetting the settings, the proximity sensor calibration may be lost to restore it:
- Go to Settings. → The phone.
- Tap 7 times on the line version of MIUI (activated developer mode).
- Back to Settings → Additionally. → For developers.
- Find the Calibration point of the proximity sensor and follow the instructions.
⚠️ Attention! Some models (POCO X3, Redmi Note 9) may not have calibration on the menu, and only resetting or firmware will help.
Reason 2: Bug in the latest MIUI update
Xiaomi regularly releases updates, but sometimes they contain errors. For example, in MIUI 14.0.3 for Xiaomi 12T there was a bug that caused the proximity sensor to work with a delay.
- 🔄 Reverse to the previous version of MIUI (via Settings → System Update → Three Points → Select Service Pack).
- 📥 Install the beta version of the firmware (if available for your model).
- 🧹 Clear the system cache: Settings → Memory. → Clear the cache.
If the problem has occurred after the update, check out reviews on forums (like 4PDA or Mi Community) – it’s possible that the bug is already known and Xiaomi is preparing a patch.
Reason 3: Conflict with applications
Some applications (especially those that work with calls or overlays) may interfere with the sensor.
- 🚫 Temporarily disable applications for recording conversations (Cube Call Recorder, ACR).
- 🔕 Remove launchers from third-party developers (e.g., Nova Launcher or Lawnchair).
- 🛡️ Run your phone in safe mode (press the power button → Safe Mode). If the problem is gone, one of the installed apps is to blame.
💡
If the screen only dims when calling via WhatsApp or Telegram, check the settings of these messengers. WhatsApp, for example, has a separate option "Scream during the call" in the section Storage and data → Data Use.
4. Hardware malfunctions: when to carry in the service
If the software methods didn't work, the problem is probably the hardware.
| Malfunction | Signs. | Decision |
|---|---|---|
| Sensor plume damaged. | The screen dims chaotically, the sensor does not respond to the tests | Replacement of the plume (from 800) ₽) |
| Cracking in glass above sensor | Visible damage, sensors run through time | Replacement of glass (from 1,500 ₽) or the entire display module |
| Oxidation of contact on board | The problem occurs when high humidity | Ultrasound board cleaning (from 1,000 ₽) |
| Battery malfunction | Phone turns off when you call, battery bloated | Battery replacement (from 1,200 ₽) |
🔧 How do you check the sensor plume? Carefully press the area around the front camera. If you press the sensor, the plume has moved away and needs to be soldered or replaced.
⚠️ Attention! If you notice that the phone is heating up when you call, or the screen is flashing before you turn off, you may be short-circuiting the circuit board.
- 🔌 Connect charging during a conversation.
- 🔥 Use your phone before repair (fire risk!)
5 Step-by-step: what to do if the screen dims when you call
So, gather your thoughts and follow this algorithm, start with the simplest steps and only get to the hard ones if the previous ones didn't work.
Clean the proximity sensor from dirt | Check the sensor through the engineering menu | Calibrate the sensor in the developer settings | Update MIUI to the latest version |Reset the phone settings | Check the phone for hardware damage | Contact the service center-->
Step 1: Clean the sensor
Take this:
- 🧴 Cotton swab dipped in alcohol (at least 70%).
- 🕯️ Fen (for drying).
Gently wipe the sensor area (don't press hard!) Then dry 2-3 minutes with a hairdryer at minimum power.
Step 2: Resetting settings
If the sensor is working, but the problem remains, reset:
- Make a backup of the data (Settings → About Phone → Backup).
- Go to Settings → About the phone → Reset settings.
- Select Reset all settings (does not delete files, only settings).
Step 3: Flashing
For power users, if the reset didn't work, you can reflash the phone via Fastboot or Recovery. For instructions for your model, look for 4PDA or XDA Developers.
⚠️ Attention! The wrong firmware can turn a phone into a brick. If you're not sure, you better put it in service.
6. Frequent questions about Xiaomi models
Some Xiaomi models have unique proximity sensor problems.
Xiaomi Redmi Note 10/11/12
These phones often have false sensor alerts because of the poor quality protective film that comes with the package.
- 📱 Remove the factory film and replace it with glass (preferably with a sensor cutout).
- 🔧 Update the firmware to MIUI 13.0.5 or later — these versions fix the sensor bug.
POCO F3/F4/F5
The POCO has a problem often with the AMOLED- screen not working properly.
- 🌓 Turn off adaptive brightness (Settings → Display → Adaptive Brightness).
- 🔄 Enable and turn off Reading Mode (Settings → Display → Read Mode).
Xiaomi 12/13/14
On flagships, the problem is usually related to a conflict between MIUI and Google's shell.
- 📦 Remove updates for the Phone app (Settings → Apps → Phone → Three Dots → Remove Updates).
- 🔒 Disable battery optimization for the Phone app.
How to turn off battery optimization?
7.Prevention: How to avoid sensor problems in the future
To ensure that the proximity sensor is stable:
- 🛡️ Use high-quality protective glass with a cutout under the sensor.
- 🚿 Avoid getting moisture into the front chamber area.
- 🔄 Update MIUI regularly (but watch for new reviews!).
- 🧴 Clean the sensor every 2-3 months with alcohol.
If you drop your phone frequently, consider a case with enhanced corner protection – this will reduce the risk of damage to the sensor plume.
💡
On models with infrared sensors (such as Xiaomi 11T), never paste opaque film — it blocks the signal. Use only transparent glass or film with a cutout.